For downward breakouts, use the price of B as the stop price. For example, if the breakout is upward, a stop at any of the minor lows on side A would work well. Click the link on the left for stop placement Place a stop loss order on the side opposite the breakout unless that would be too far away. The associated link provides more information. Compute the height from the price of the horizontal trendline (B) to the lowest valley in the pattern (A) and then multiply itīy the above 'percentage meeting price target.' Add it (upward breakouts) or subtract it (downward breakouts) from the breakout price.
